Ignition proving systems

ABSTRACT

Ignition-proving systems utilizing a holding coil in parallel with an electric igniter, a heat expansible wire in series with the igniter, and first and second switches controlled by the coil and wire, respectively, to control the operation of a fuel valve whereby the system assumes a fail-safe state in response to any failures of components or electricity.

e V United States Patent 1 1 3,619,096

[72] lnventors KelthT.Krueger [56-] RelenencesClted Garden Grove; UNITED STATES PATENTS 3,393,038 7/1968 Burkhalteretal. 43l/66 12!] PP 856,749 3,457,020 7/1909 Hine 431/00 1 Flled 3,488,132 1/1970 Fairleyelal. 43l/66 i kc 3,502,419 3/1970 Perl 431/01) ss1gnee 0 SW on 1'0 ompany Richmond. vm FOREIGN PATENTS 73,813 9/l960 France 431/66 [54] IGNITION PROVING SYSTEMS 28 Claims, 5 Drawing Figs.

[52] U.S.Cl 431/66 [5 l] Int. Cl F2311 5/02 [50] Field of Search 43l/66; 3 l 7/79, 98

Primary Examiner-- Edward G. Favors Almrneys-Anthony A. O'Brien, Auzvillc Jackson. Jr. and

Robert L. Marben ABSTRACT: Ignition-proving systems utilizing a holding coil in parallel with an electric igniter. a heat expansible wire in series with the igniter. and first and second switches controlled by the coil and wire, respectively. to control the operation ofu fuel valve whereby the system assumes a fail-safe state in response to any failures of components or electricity.

PATENTEDunv 9 Ian SHEET 1 BF 2 l I l l J FIG.

54 INVENTORS,

Keith T. Krueger Hugh J. Tyler I IV. M14

ATTORNEY BACKGROUND OF THE INVENTION The present invention pertains to ignition-proving systems and more particularly to ignition-proving systems for an electric igniter having a positive temperature coefficient of resistance.

The recent trend in the field of igniting such devices as fuel burners is to utilize electric igniters in place of standing pilot flames. When using such igniters it has been found that burner operation can be monitored by the igniter itself if the igniter element is constructed of a material having a resistance varying with temperature. That is, the resistance of the igniter is a function of the temperature at the igniter, and by sensing the resistance the operation of the igniter and burner may be proved.

Due to the inherently dangerous conditions resulting from improper operation of ignition systems, it is required that the systems be shut down upon the failure of any components or interruption of electricity. More specifically, it is important that the valve supplying fuel to the burner be open only when igniting temperatures exist to prevent a build up of raw fuel. It is also desirable to have the system recycle when igniting temperatures are not timely provided, once electricity is restored after an interruption or when the valve is closed due to other failures in the system such that another attempt is made to initiate ignition whereby burner operation is not restricted when the system is capable of proper operation.

While, as previously mentioned, the resistance of electric igniters has been used in ignition-proving systems, such systems have been crude and have not provided the comprehensive fail-safe or recycling characteristics required. Furthermore, such ignition-proving systems have not taken full advantage of the temperature-variable resistance characteristics of electric igniter elements.

SUMMARY OF THE INVENTION Accordingly it is an object of the present invention to construct an ignition-proving system utilizing the varying resistance of an electric igniter with temperature.

Another object of the present invention is to utilize an igniter having a positive temperature coefficient of resistance as a sensor and control element as well as for ignition.

A further object of the present invention is to utilize current-sensitive means in series with an igniter having a positive temperature coefiicient of resistance to control the operation of a valve in accordance with temperature at the igniter.

The present invention has another object in that voltagesensing means is in parallel with an igniter having a positive temperature coefficient of resistance to control the operation of a valve in accordance with temperature at the igniter.

Another object of the present invention is to sense the current through and the voltage across an igniter having a positive temperature coefficient of resistance in an ignition-proving system.

A further object of the present invention is to utilize a holding coil in parallel with an igniter to control a switch and a heat expansible wire in series with the igniter to control another switch with both switches controlling the operation of a valve.

Some of the advantages of the ignition-proving system of the present invention are that an igniter is utilized as a combination igniter and temperature sensor, the system is fail-safe, the system is extremely sensitive, and the system recycles after a failure to attempt to initiate ignition again.

The present invention is generally characterized in an ignition-proving system having input means, an electric igniter, a valve, switch means connecting the electric igniter and the valve with the input means, first control means responsive to igniter voltage to control the switch means, and second control means responsive to igniter current to control the switch means. The present invention is further generally characterized in an ignition proving system having an electric igniter,

a valve, current-sensing means connected with the igniter, and control means coupled with the current-sensing means and controlling the valve in response to current through the igniter.

Further objects and advantages of the present invention will become apparent from the description of the preferred embodiment as shown in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a first embodiment of the present invention.

FIG. 2 is a schematic diagram of the embodiment of FIG. I after successful ignition.

FIG. 3 is a schematic diagram of the embodiment of FIG. 1 in its fail-safe state.

FIG. 4 is a schematic diagram of another embodiment of the present invention.

FIG. 5 is a schematic diagram of a further embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the ignition proving system of the present invention is illustrated in FIGS. 1, 2 and 3 for use with a fuel burner 10. An electrically operated fuel valve 12 communicates with burner 10 and any suitable source of fuel, not shown, to control the flow of fuel to burner 10. Valve 12 may be controlled by any suitable electrical operator such as a solenoid or a heatmotor. An electric igniter 14 is disposed in igniting proximity to the ports of burner 10. Igniter I4 is constructed of a material having a positive temperature coefficient of resistance, such as molybdenum disilicide.

A housing 16 indicated by dashed lines has a pair of input terminals 18 and 20 which are connected with the secondary winding 22 of a transformer 24 having a primary winding 26 connected to a suitable source of electricity, not shown, through a thermostatic switch 28. Terminal 18 is connected to a stationary contact arm 30 which is secured to housing l6 and carries a contact 32. A contact 34 cooperates with contact 32 to provide a switch generally indicated at 36.

Contact 34 is carried by a movable contact arm 38 which has one end pivotally mounted on a pin 40 in housing 16. A helical bias spring 42 is mounted in compression between the upper side of movable contact arm 38 and housing 16. The free end 44 of movable contact arm 38 carries an ear 46 having an aperture therein for receiving the end of a tension spring 48. The other end of spring 48 is inserted in an aperture of an ear 50 carried by a long leg 52 of an L-shaped lever 54. Lever 54 is pivotally mounted in housing 16 on a pin 56, and a short leg 58 of lever 54 is secured to one end of an electrically conductive hot wire 60. The other end of hot wire 60 is secured to housing 16 by a screw 62 and is electrically connected with terminal 20. Hot wire 60 has a thermal expansion characteristic such that it expands as it heats and it contracts as it cools. At normal room temperature hot wire 60 is in a relatively contracted state as shown in FIG. I.

A helical bias spring 64 is mounted in compression between housing 16 and the free end ofleg 52 of lever 54. An upstanding finger 66 is secured to the upper side of leg 52 of lever 54 and has an arcuate shoulder 68 adapted to abut the underside of movable contact arm 38. A ring 70 is carried by finger 66 and is adapted to abut the underside of a movable contact arm 72 which is pivotally mounted in housing 16 on a pin 74. A bias spring 76 is mounted in compression between the underside of movable contact arm 38 and the upper side of contact arm 72. Contact arm 72 carries a contact 78 which cooperates with a contact 80 to form a switch generally indicated at 82. Contact 80 is carried by a stationary contact arm 84 which is secured to housing 16.

Housing 16 has three output terminals 86, 88 and 90. Terminal 86 is electrically connected with contact arms 38 and 72 within housing 16 and is connected through a lead 92 to a terminal 94 of igniter 14. The other terminal 96 of igniter I4 is connected to tenninal 88 through a lead 98, and terminal 88 is connected with hot wire 60 within housing 16 through a lead 100. Terminal 90 is connected to contact 84 within housing 16 and is connected through a lead 102 to a terminal 104 of fuel valve 12. The other terminal 106 of fuel valve 12 is connected through lead 108 to input terminal 20.

A holding coil 110 has two legs which are connected in parallel with igniter 14 through leads I12 and 114. A center tap 116 for coil 110 is coupled to lead 112 through an input terminal 118 of housing 116. Lead 114 is connected through an input terminal 120 of housing 16 and oppositely poled full wave rectifying diodes 122 and 124 to the two legs of coil 1 10. An armature 126 is controlled by coil 110 and is secured to the upper side of movable contact arm 38.

In operation, thermostatic switch 28 will normally be open and the ignition proving system will have an initial state as illustrated in FIG. 1. That is, no power will be supplied to the system with switch 28 open, and fuel valve 12 will be closed with igniter l4 deenergized. Hot wire 60 is cold since no current is flowing therethrough and is, therefore, contracted to pivotally move arm 52 counterclockwise against the force of spring 64 such that finger 66 moves contact arm 38 up against the force of spring 42 to close contacts 32 and 34 of switch 36. Contacts 78 and 80 of switch 82 are open at this time due to contact arm 72 following ring 70 in finger 66.

Once thermostatic switch 28 is closed signalling a need for burner operation, current will flow from terminal 18 through switch 36, lead 92, igniter 14, leads 98 and 100, and hot wire 60 to terminal 20 to energize igniter 14 and begin heating hot wire 60. Since igniter 14 has a positive temperature coefficient of resistance, the initial voltage drop thereacross is small and insufficient to pull in coil 110 and most of the initial voltage drop is across hot wire 60. It is noted that coil 110 must be very sensitive to voltage across igniter l4; and, therefore, coil 110 is not required to pull in armature 126 to close switch 36 but must merely hold armature 126 since switch 36 is closed at the start of operation.

The current flowing through hot wire 60 causes it to heat and expand thereby permitting spring 64 to rotate lever 54 clockwise. The movement of lever 54 moves finger 66 such that contact arm 72 is pivoted clockwise by spring 70 and contact arm 38 is free to pivot clockwise, as shown in FIG. 2 which illustrates the state of the ignition-proving system after successful ignition. If igniter 14 has reached ignition temperature by the time shoulder 68 of finger 66 moves away from contact arm 38, the resistance of igniter 14 will be high due to the positive temperature coefficient of resistance; and, accordingly, the voltage drop thereacross will be sufficient to energize holding coil 110 and maintain switch 36 closed. That is, since coil 110 is connected in parallel with igniter 14, it experiences the same voltage drop, and coil 110 will be sufficiently energized to hold armature 126 only when igniter 14 is at ignition temperature. Diodes 122 and 124 provide full wave rectified current to holding coil to eliminate noise and chatter when the coil is near its dropout point.

Switch 82 is closed by the clockwise movement of contact arm 72, and valve 12 is energized by current flowing from terminal 18 through switch 36, switch 82 and leads 102 and 108 to terminal 20. Thus, when igniter 14 reaches ignition temperature within the predetermined time between closure of thermostatic switch 28 and expansion of hot wire 60, valve 12 will be opened to supply fuel to burner 10.

if for any reason igniter l4 fails to reach ignition temperature by the time the current through hot wire 60 heats the wire sufficiently such that expansion permits spring 65 to move lever 54 clockwise, switch 36 will be opened since contact arm 38 will follow finger 66 due to the force from spring 42. Once switch 36 is opened all electricity from secondary winding 22 is interrupted; and, accordingly, igniter 14 is deenergized and valve I2 is closed. Thus, it can be seen that valve 12 depends on the operation of both switches 36 and 82 which are in series and that valve 12 will not open unless igniter 14 is at ignition temperature. Contacts 32 and 34 of switch 36 will break prior to the making of contacts 78 and 80 of switch 82 thereby assuring that upon failure of igniter 14 to reach ignition temperature within the predetermined time, valve 12 will not be opened.

Opening of switch 36 also prevents current from flowing through hot wire 60 thereby permitting hot wire 60 to cool and contract moving lever 54 counterclockwise and permitting finger 66 to close contacts 32 and 34 of switch 36. Thus, the system is returned to the state shown in FIG. 1 and will recycle until igniter 14 properly reaches ignition temperature within the predetermined time.

If during normal operation of the ignition proving system, as shown in FIG. 2, any type of electrical interruption occurs, holding coil will be deenergized to drop out armature 126 and permit the force from bias spring 42 to open switch 36 thereby disconnecting igniter 14, closing valve 12 and stopping the flow of current through hot wire 60. The system is thus placed in a fail-safe state, as shown in FIG. 3.

Since no current passes through hot wire 60 the wire will cool and contract causing lever 54 to move counterclockwise to place the system in the state shown in FIG. 1 thereby permitting recycling. That is, if thermostatic switch 28 remains closed when power is returned, the burner will be igniter in the same manner as previously described.

If igniter 14 is ruptured once the system is in its operating state shown in FIG. 2, the voltage across holding coil 10 will increase substantially to prevent switch 36 from opening; however, since hot wire 60 is in series with igniter 14 the current flowing through hot wire 60 will be interrupted to cool the wire. As previously mentioned, hot wire 60 will contract as it cools to move lever 54 counterclockwise to cause finger 66 to lift contact arm 72 and open switch 82 thereby closing valve 12. The system will remain in this condition until igniter 14 is replaced.

If igniter 14 should become short circuited the voltage thereacross will decrease to zero; and, accordingly, coil 110 will drop out to open switch 36 and close valve 12. If hot wire 60 is broken, the current path through igniter 14 will be opened to drop out holding coil I10 and permit contact arm 38 to follow lever 54 under the force of spring 42 to open switch 36. If a short circuit occurs across hot wire 60, the wire will be cool and contracted thereby maintaining switch 82 open due to the lifting of contact arm 72.

In the event of a failure due to igniter 14 being cooled, such as by the fuel stream, the voltage across igniter l4 and holding coil 110 will be reduced due to the drop in resistance of igniter 14 as it is cooled. It has been found that igniter cooling can occur to the extent that ignition is prevented while the decreased voltage drop across igniter 14 is insufficient to drop out holding coil 110. To render the system of the present invention fail-safe for such igniter cooling, spring 48 is mounted in tension between lever 54 and movable contact arm 38. The decrease in the resistance of igniter 14 upon cooling causes the current flowing through hot wire 60 to increase and this increase causes further expansion permitting lever 54 to increase its movement in the clockwise direction. This increased movement of lever 54 stretches spring 48 to increase the clockwise force on movable contact arm 38 permitting armature 126 to be released by holding coil 110 even though the voltage across holding coil 110 is at a higher than normal value. Thus it can be seen that the system of the present invention is extremely sensitive to external conditions that might cool igniter 14 since armature 126 responds to the voltage across igniter 14 and the current through igniter 14. That is, the system of the present invention can assume a fail-safe state in response to internal or external failure even when the supply voltage is increased or decreased below normal values since an increase in voltage will increase the current through hot wire 60 therefore tending to open switch 36, and a decrease in voltage will tend to drop out holding coil 110 to open switch 36.

A modification of the embodiment of FIG. 1 is illustrated in FIG. 4 and parts identical to parts in FIG. 1 are given identical reference numerals and are not described again.

The ignition proving system of FIG, 4 differs from the em bodiment of FIG. I basically in that fuel valve 12 is connected directly in parallel with hot wire 60 rather than in parallel with both igniter 14 and hot wire 60, as in the embodiment of FIG. 1. Thus, lead 102 from valve 12 is connected to an output terminal 128 which is connected within housing 16 to movable contact arm 72. A lead 130 connects terminal 88 with terminal 90 such that current paths after successful ignition may be traced from terminal 18 through switch 36, lead 92, igniter 14, leads 98 and 100 and hot wire 60 to tenninal 20 and from terminal 18 through switch 36, lead 92, igniter 14, leads 98 and 130, switch 82, lead 102, valve 12 and lead 108 to terminal 20. Since valve 12 is directly in parallel with hot wire 60, hot wire 60 is more sensitive to current changes in the system.

The operation of the system of FIG. 4 is the same as that previously described with respect to FIGS. 1, 2 and 3 and will not be described again for the sake of brevity.

A further modification of the embodiment of FIG. 1 is illustrated in FIG. 5 and parts identical to parts in FIG. 1 are given identical reference numerals and are not described again. Parts similar to parts in FIG. 1 are given reference numerals with 200 added.

The ignition proving system of FIG. 5 differs from the embodiment of FIG. 1 in that transformer 224 has a tapped secondary winding forming legs 222 and 223 in order to provide a higher voltage for valve 12. Thus, lead 108 from valve 12 is connected to an input terminal 221, and input tenninal 20 acts as a center tap. In order to prevent valve 12 from being exposed to half of the secondary voltage, a three-way switch 236 is utilized in place of switch 36 of FIG. 1. Switch 236 includes a contact blade 234 carried by movable contact arm 38, contact 32 and a contact 235 carried by a stationary contact arm 237 which is secured to housing 16. Contact arm 237 is connected with an output terminal 286 through a lead 239.

In operation, the system of FIG. 5 is similar to that described with respect to FIGS. 1, 2 and 3. Once thermostatic switch 28 is closed, igniter 14 is energized by current flowing from terminal 18 through switch 236, leads 239 and 92, igniter 14, leads 98 and 100, and hot wire 60 to terminal 20. Valve 12 remains open at this time since switch 82 is open; however, once hot wire 60 heats and expands valve 12 will close due to the current flowing from terminal 18 through switch 236, switch 82, lead 102, valve 12, and lead 108 to terminal 221 if igniter 14 is at ignition temperature as previously explained with respect to the embodiment of FIG. 1.

The embodiments of FIGS. 4 and 5 are fail-safe in the same manner as previously described with respect to FIGS. 1, 2 and Thus, it may be seen that the ignition-proving systems of the present invention fully utilize the temperature varying resistance of electric igniters by sensing the current therethrough and the voltage thereacross to provide fail-safe operation. Furthermore, the voltage and current sensing and control means cooperate in such a manner that an increase in current permits the dropout voltage to be increased.

In as much as the present invention is subject to many variations, modifications and changes in detail, it is intended that all matter described in the foregoing specification or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. An ignition-proving system for a fuel burner comprising input means adapted to be connected to a source of electricity;

electric igniter means adapted to be positioned in igniting proximity to the burner;

valve means adapted to control a flow of fuel to the burner;

switch means connecting said electric igniter means and said valve means with said input means;

first control means connected in circuit with said electric igniter means, said first control means being coupled to said switch means and responsive to the voltage across said electric igniter means to control the operation of said switch means; and

second control means disposed at a position remote from heating proximity of said electric igniter means and connected in circuit with said electric igniter means to sense electrical current flowing therethrough, said second control means being coupled to said switch means and directly responsive to the sensed current flowing through said electric igniter means to control the operation of said switch means whereby operation of said valve means is dependent on the sensed operating characteristics of said electric igniter means.

2. The invention as recited in claim 1 wherein said switch means includes a first switch controlled by said first control means and a second switch controlled by said second control means, said first switch and said second switch being connected in series between said input means and said valve means whereby said first switch and said second switch must be closed to open said valve means.

3. The invention as recited in claim 1 wherein said electric igniter means has a positive temperature coefficient of resistance, and said first control means is connected in parallel with said electric igniter means.

4. The invention as recited in claim 3 wherein said electric igniter means exhibits a high resistance when at igniting temperature, and said first control means includes a holding coil.

5. The invention as recited in claim 4 wherein said electric igniter means has first and second terminals, said holding coil has first and second legs joined at a tap, said tap is connected to said first terminal of said electric igniter means, said first leg is connected through a first diode to said second terminal of said electric igniter means, and said second leg is connected through a second diode to said second terminal of said electric igniter, said first and second diodes being poled in opposite directions.

6. The invention as recited in claim 3 wherein said second control means is connected in series with said electric igniter means.

7. The invention as recited in claim 6 wherein said first control means includes a holding coil and said second control means includes a heat expansible wire.

8. The invention as recited in claim 7 wherein said switch means includes a first switch controlled by said first control means and a second switch controlled by said second control means, said first switch and said second switch being connected in series between said input means and said valve means.

9. The invention as recited in claim 8 wherein said switch means includes lever means connected with and movable by said wire and controllably connected with said first and second switches.

10. The invention as recited in claim 9 wherein said first switch is normally closed and includes a contact arm carrying an armature under the control of said holding coil, said contact arm being biased toward said lever means, and said wire has a cool contracted state defining a first position for said level means and a hot expanded state defining a second position for said lever means, said lever means closing said first switch when said lever means is in said first position.

11. The invention as recited in claim 10 wherein said electric igniter means has a high resistance at igniting temperatures, said second switch is open when said lever means is in said first position and closed when said lever means is in said second position, and said holding coil is energized to hold said armature and maintain said first switch closed when said electric igniter means has said high resistance whereby energization of said electric igniter means places said wire in said hot expanded state and said lever means in said second position to close said second switch, said first switch remaining closed if said electric igniter means is at ignition temperature to open said valve means and said first switch opening if said electric igniter means is not at ignition temperature.

12. The invention as recited in claim 11 wherein said valve means is connected in parallel with said wire.

13. The invention as recited in claim 11 wherein said input means includes a secondary winding having a first terminal, a second terminal and a tap, said valve means being connected with said first terminal and said wire being connected with said tap, and said first switch having a first contact connected with said second terminal, a second contact connected with said electric igniter means and a third contact carried by said contact arm, connected with said second switch and adapted to contact said first and second contacts.

14. The invention as recited in claim 11 wherein a spring is mounted in tension between said contact arm and said lever means whereby increased current through said wire increases the voltage across said electric igniter means at which said armature will be released by said holding coil.

15. The invention as recited in claim 1 wherein means is connected between said switch means and said second control means to increase the voltage across said electric igniter means at which said first control means is operated when the current through said electric igniter means is increased.

16. An ignition-proving system for a fuel burner comprising input means adapted to be connected to a source of electricity;

an electric igniter connected with said input means and adapted to be positioned in igniting proximity to the burner, said electric igniter having a positive temperature coefficient of resistance such that current flowing therethrough is dependent on the temperature of said electric igniter;

valve means adapted to control a flow of fuel to the burner;

current-sensing means connected in series with said electric igniter and including a heat expansible wire heated by current passing therethrough;

control means coupled with said current-sensing means and said valve means to control said valve means in response to the amount of sensed current passing through said electric igniter; and

said control means including a lever connected with and movable by said wire and a switch connected in series with said valve means and said input means, said lever controlling the operation of said switch whereby said valve means is responsive to the sensed temperature of said electric igniter.

17. A control module for a fuel burner ignition system comprising a housing;

first switch means mounted in said housing;

second switch means mounted in said housing;

first control means in said housing connected with said first switch means to control the operation of said first switch means in response to a first sensed electrical parameter; and

second control means in said housing connected with said first and second switch means to control the operation of said first and second switch means in response to a second sensed electrical parameter.

18. The invention as recited in claim 17 wherein said first switch means is electrically connected in series with said second switch means.

19. The invention as recited in claim 17 wherein said first control means includes a holding coil.

20. The invention as recited in claim 19 including a pair of electrical terminals on said housing, and wherein said holding coil has first and second legs joined at a tap, said tap is connected to one of said pair of electrical terminals, said first leg is connected through a first diode to the other of said pair of electrical terminals, and said second leg is connected through a second diode to said other terminal, said first and second diodes being poled in opposite directions.

27. The invention as recited in claim 19 wherein said second control means includes a heat expansible wire and lever means connected with and movable by said wire, and said lever means is connected with said first and second switch means.

22. The invention as recited in claim 21 wherein said first switch means includes a movable contact arm carrying an armature under the control of said holding coil and a spring biasing said contact arm toward said lever means, and wherein said wire has a contracted state defining a first position for said lever means and an expanded state defining a second position for said lever means, said lever means closing said first switch when said lever means is in said first position.

23. The invention as recited in claim 22 wherein said second switch means includes a movable contact arm and a spring biasing said contact arm toward said lever means, said lever means opening said second switch means when said lever means is in said first position and closing said second switch means when said lever means is in said second position, said first switch means being opened by said lever means before said second switch means is closed by said lever means as said lever means is moved by said wire from said first to said second position.

24. The invention as recited in claim 23 including bias means connected with said lever means and said movable contact arm of said first switch means to open said first switch means upon movement of said lever means beyond said second position.

25. The invention as recited in claim 24 wherein said movable contact arm of said first switch means is electrically connected with said movable contact arm of said second switch means.

26. The invention as recited in claim 21 wherein said lever means includes a generally L-shaped lever arm carrying a finger engaging said first switch means to control the same.

27. The invention as recited in claim 26 wherein said finger of said lever arm carries a ring engaging said second switch means to control the same.

28. The invention as recited in claim 17 wherein said first switch means includes a first fixed contact, a second fixed contact, and a third contact carried by a movable contact arm, said third contact adapted to contact said first and second fixed contacts. 

1. An ignition-proving system for a fuel burner comprising input means adapted to be connected to a source of electricity; electric igniter means adapted to be positioned in igniting proximity to the burner; valve means adapted to control a flow of fuel to the burner; switch means connecting said electric igniter means and said valve means with said input means; first control means connected in circuit with said electric igniter means, said first control means being coupled to said switch means and responsive to the voltage across said electric igniter means to control the operation of said switch means; and second control means disposed at a position remote from heating proximity of said electric igniter means and connected in circuit with said electric igniter means to sense electrical current flowing therethrough, said second control means being coupled to said switch means and directly responsive to the sensed current flowing through said electric igniter means to control the operation of said switch means whereby operation of said valve means is dependent on the sensed operating characteristics of said electric igniter means.
 2. The invention as recited in claim 1 wherein said switch means includes a first switch controlled by said first control means and a second switch controlled by said second control means, said first switch and said second switch being connected in series between said input means and said valve means whereby said first switch and said second switch must be closed to open said valve means.
 3. The invention as recited in claim 1 wherein said electric igniter means has a positive temperature coefficient of resistance, and said first control means is connected in parallel with said electric igniter means.
 4. The invention as recited in claim 3 wherein said electric igniter means exhibits a high resistance when at igniting temperature, and said first control means includes a holding coil.
 5. The invention as recited in claim 4 wherein said electric igniter means has first and second terminals, said holding coil has first and second legs joined at a tap, said tap is connected to said first terminal of said electric igniter means, said first leg is connected through a first diode to said second terminal of said electric igniter means, and said second leg is connected through a second diode to said second terminal of said electric igniter, said first and second diodes being poled in opposite directions.
 6. The invention as recited in claim 3 wherein said second control means is connected in series with said electric igniter means.
 7. The invention as recited in claim 6 wherein said first control means includes a holding coil and said second control means includes a heat expansible wire.
 8. The invention as recited in claim 7 wherein said switch meaNs includes a first switch controlled by said first control means and a second switch controlled by said second control means, said first switch and said second switch being connected in series between said input means and said valve means.
 9. The invention as recited in claim 8 wherein said switch means includes lever means connected with and movable by said wire and controllably connected with said first and second switches.
 10. The invention as recited in claim 9 wherein said first switch is normally closed and includes a contact arm carrying an armature under the control of said holding coil, said contact arm being biased toward said lever means, and said wire has a cool contracted state defining a first position for said level means and a hot expanded state defining a second position for said lever means, said lever means closing said first switch when said lever means is in said first position.
 11. The invention as recited in claim 10 wherein said electric igniter means has a high resistance at igniting temperatures, said second switch is open when said lever means is in said first position and closed when said lever means is in said second position, and said holding coil is energized to hold said armature and maintain said first switch closed when said electric igniter means has said high resistance whereby energization of said electric igniter means places said wire in said hot expanded state and said lever means in said second position to close said second switch, said first switch remaining closed if said electric igniter means is at ignition temperature to open said valve means and said first switch opening if said electric igniter means is not at ignition temperature.
 12. The invention as recited in claim 11 wherein said valve means is connected in parallel with said wire.
 13. The invention as recited in claim 11 wherein said input means includes a secondary winding having a first terminal, a second terminal and a tap, said valve means being connected with said first terminal and said wire being connected with said tap, and said first switch having a first contact connected with said second terminal, a second contact connected with said electric igniter means and a third contact carried by said contact arm, connected with said second switch and adapted to contact said first and second contacts.
 14. The invention as recited in claim 11 wherein a spring is mounted in tension between said contact arm and said lever means whereby increased current through said wire increases the voltage across said electric igniter means at which said armature will be released by said holding coil.
 15. The invention as recited in claim 1 wherein means is connected between said switch means and said second control means to increase the voltage across said electric igniter means at which said first control means is operated when the current through said electric igniter means is increased.
 16. An ignition-proving system for a fuel burner comprising input means adapted to be connected to a source of electricity; an electric igniter connected with said input means and adapted to be positioned in igniting proximity to the burner, said electric igniter having a positive temperature coefficient of resistance such that current flowing therethrough is dependent on the temperature of said electric igniter; valve means adapted to control a flow of fuel to the burner; current-sensing means connected in series with said electric igniter and including a heat expansible wire heated by current passing therethrough; control means coupled with said current-sensing means and said valve means to control said valve means in response to the amount of sensed current passing through said electric igniter; and said control means including a lever connected with and movable by said wire and a switch connected in series with said valve means and said input means, said lever controlling the operation of said switch whereby said valve means is rEsponsive to the sensed temperature of said electric igniter.
 17. A control module for a fuel burner ignition system comprising a housing; first switch means mounted in said housing; second switch means mounted in said housing; first control means in said housing connected with said first switch means to control the operation of said first switch means in response to a first sensed electrical parameter; and second control means in said housing connected with said first and second switch means to control the operation of said first and second switch means in response to a second sensed electrical parameter.
 18. The invention as recited in claim 17 wherein said first switch means is electrically connected in series with said second switch means.
 19. The invention as recited in claim 17 wherein said first control means includes a holding coil.
 20. The invention as recited in claim 19 including a pair of electrical terminals on said housing, and wherein said holding coil has first and second legs joined at a tap, said tap is connected to one of said pair of electrical terminals, said first leg is connected through a first diode to the other of said pair of electrical terminals, and said second leg is connected through a second diode to said other terminal, said first and second diodes being poled in opposite directions.
 21. The invention as recited in claim 19 wherein said second control means includes a heat expansible wire and lever means connected with and movable by said wire, and said lever means is connected with said first and second switch means.
 22. The invention as recited in claim 21 wherein said first switch means includes a movable contact arm carrying an armature under the control of said holding coil and a spring biasing said contact arm toward said lever means, and wherein said wire has a contracted state defining a first position for said lever means and an expanded state defining a second position for said lever means, said lever means closing said first switch when said lever means is in said first position.
 23. The invention as recited in claim 22 wherein said second switch means includes a movable contact arm and a spring biasing said contact arm toward said lever means, said lever means opening said second switch means when said lever means is in said first position and closing said second switch means when said lever means is in said second position, said first switch means being opened by said lever means before said second switch means is closed by said lever means as said lever means is moved by said wire from said first to said second position.
 24. The invention as recited in claim 23 including bias means connected with said lever means and said movable contact arm of said first switch means to open said first switch means upon movement of said lever means beyond said second position.
 25. The invention as recited in claim 24 wherein said movable contact arm of said first switch means is electrically connected with said movable contact arm of said second switch means.
 26. The invention as recited in claim 21 wherein said lever means includes a generally L-shaped lever arm carrying a finger engaging said first switch means to control the same.
 27. The invention as recited in claim 26 wherein said finger of said lever arm carries a ring engaging said second switch means to control the same.
 28. The invention as recited in claim 17 wherein said first switch means includes a first fixed contact, a second fixed contact, and a third contact carried by a movable contact arm, said third contact adapted to contact said first and second fixed contacts. 